Ambassador Bashar Ja’afari says the attacks occurred on Aug. 22, 24 and 25 in three suburbs of the Syrian capital and dozens of soldiers are being treated for inhaling nerve gas.

Ja’afari says he sent a letter to Secretary-General Ban Ki-moon asking that chemical weapons experts now in Damascus investigate the incidents. The U.N. team is investigating an alleged chemical weapons attack that reportedly killed 355 people, which the U.S. and its allies have blamed on the Syrian regime.

Ja’afari spoke to reporters Wednesday near a room where the five permanent Security Council members discussed a British-proposed resolution to authorize the use of military force against Syria.